Send a transactional email

Transactional email — receipts, resets, confirmations — is a single POST /api/v1/emails. These always deliver, even to unsubscribed contacts, because they're not marketing (unsubscribe blocks only marketing templates).

Send nowCopy Anchor Link

import { SendAndRetain } from "@sendandretain/sdk";

const sendandretain = new SendAndRetain(); // reads SENDANDRETAIN_API_KEY

const { data, error } = await sendandretain.emails.send(
  {
    to: "[email protected]",
    template: "receipt",
    props: { orderId: "ord_991", total: "42.50" },
    from: "Acme <[email protected]>",
  },
  { idempotencyKey: "receipt-ord-991" },
);

from is optional — omit it to use the project's default sender. It must resolve to a verified domain.

Schedule for laterCopy Anchor Link

Pass an ISO 8601 scheduled_at in the future; the worker sends it at that time. Scheduling is handled by Send & Retain (not the provider), so it's uniform across providers and cancellable.

{ "to": "[email protected]", "template": "reminder", "scheduled_at": "2026-08-01T09:00:00Z" }

Attach filesCopy Anchor Link

Attachments are base64-encoded, up to 10 per message and ~5 MB total:

{
  "to": "[email protected]",
  "template": "invoice",
  "attachments": [
    { "filename": "invoice.pdf", "content": "JVBERi0xLjQK...", "content_type": "application/pdf" }
  ]
}

IdempotencyCopy Anchor Link

Always pass an Idempotency-Key for sends you might retry — see Idempotency. A repeat returns the original result with deduplicated: true.

Full referenceCopy Anchor Link